The invention relates to a lock fitted to a door and comprising a bolt movable in a straight line between an extended position and a retracted position, means for urging the bolt to its extended position, means for returning the bolt from its extended position to its retracted position, movably coupled to the bolt, a combination disk, comprising a notch and stop means, mounted for rotation on a shaft, a drive disk mounted for rotation on said shaft comprising stop means cooperating with those of the combination disk in a given relative angular position of these disks, and first means for cooperating with said bolt traction means, means for rotating the drive disk, second means for cooperating with said bolt traction means, adapted so as to be received in said notch in a given angular position of the combination disk, obtained by actuating said operating means in accordance with a coded combination, these second means being movable between a position in which they are situated outside the notch and hold the bolt traction means away from the drive disk and a position in which they are situated in the notch and allow cooperation between the bolt traction means and said first means of the drive disk, the bolt then being able to be moved to its retracted position by rotation of the drive disk.
A lock of this type is known more particularly from the document US-A-4 147 045 and operates satisfactorily.
However, it reveals a few drawbacks in use.
In such a lock, the bolt is held in a retracted position by the user who immobilizes the means for operating the drive disk, for example an operating handle. Since the bolt traction means cooperate with the drive disk, they are prisoners of this latter and effectively retain the bolt in the retracted position.
At this stage, the authorized user may block the operating handle by any appropriate means for preventing subsequent closure of the lock and thus avoid having to dial the coded combination the next time he accedes to the door.
In addition, when a finger is provided for scrambling the combination disk, mounted on the bolt for striking the combination disk when the bolt is extended, the user may try to partially neutralize the scrambling effect by braking the movement of the operating handle when it returns to an angular position corresponding to closure of the door, namely by braking the movement of the bolt traction means.